Semiconductor Microelectromechanical Systems Research Articles

Hybrid Microfluxgate and Current Transformer Sensor

In this work, we develop the hybrid current sensor comprising a microfluxgate and a current transformer (CT) for wide-bandwidth current measurement. The microfluxgate consists of two microcoil chips 3.5 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1.75$ </tex-math></inline-formula> mm in dimension made by using the standard Complementary Metal-Oxide Semiconductor MicroElectroMechanical Systems (CMOS-MEMS) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.35 ~\mu \text{m}$ </tex-math></inline-formula> process. The aluminum wire-bonding technique is used to construct the top excitation coil surrounding the amorphous soft magnetic core patterned by photolithography and wet etching techniques. Under the optimal excitation condition, the response of the microfluxgate current sensor becomes linear with a maximized sensitivity. The in-house made CT is combined with the microfluxgate driving system to form the hybrid current sensor by using a summing amplifier. The hybrid current sensor has a spectral current noise of 0.4 mA/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\surd $ </tex-math></inline-formula> Hz at 1 Hz. The maximum sensing range is ±10 A, and the non-linearity is less than 2% within the ±4.6 A range, corresponding to a linear dynamic range of 60 dB in a 10 Hz bandwidth. The hybrid microfluxgate-and-CT sensor has a flat bandwidth from dc to 100 kHz. It has the potential to become a practical miniature device featuring a high-dynamic range, wide bandwidth, and low-temperature drift.

Fabrication of Aluminum Nickel Reactive Bilayer by the Lift-Off Process

Semiconductor component and microelectromechanical system manufacturing requires metal patterning in an integrated circuit (IC), using the photoresist lift-Off process. Ideal advantages like cost-effectiveness, reduction of complexity and process maturity are associated with the lift-Off process. Alternatively, the choice of photoresist relies on factors such as cost, initial photoresist thickness and reliable processing parameters extraction. However, the availability of the cheap photoresist is still at question. For the case of the underlying study, a highly cheap photoresist E8015 of thickness 38-micrometer was developed for the purpose of edge profiling. Desirable extraction of the useful parameter range for dry resist processing is performed. Parameter variation like exposure energy and development time led to a successful undercut angle of 66° to 73°, while the straight edge profile of 90° was realized at various parameter combinations. Eventually, a metallic multilayer of 10-micrometer thickness is successfully lifted off on plain silicon. Controlled self-propagating reaction within these structured metallic layers may be employed for IC packaging hereafter.

Bidirectional CMOS-MEMS Airflow Sensor With Sub-mW Power Consumption and High Sensitivity

This article presents a bidirectional thermoresistive micro calorimetric flow (TMCF) sensor implemented by a 0.18- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m complementary metal–oxide–semiconductor microelectromechanical systems (CMOS-MEMS) technology, while the sensor thickness is thinned to 2.7 μm through an in-house developed MEMS fabrication process. For the bidirectional airflow of −6 to 6 m/s, the TMCF sensor achieves the highest sensitivity of 453 mV/(m/s), and its highest normalized sensitivity with respect to the signal amplification gain (gain = 250) and the input heating power (1.58–1.72 mW) is 1150 mV/(m/s)/W. By reducing the heating power to the sub-mW of <220 μW, the TMCF sensor can still give a remarkable sensitivity of 87.4 mV/(m/s). In addition, the developed TMCF sensor has an intrinsic minimum detectable flow velocity of 99 μm/s and a response time of 4.8 ms. The performance achieved by this flow sensor enables accurate indoor airflow measurements even when dealing with the extremely low-speed flow (<0.05 m/s). Furthermore, the high-performance TMCF sensor is applied for remote human motion detection, where different walking speeds and moving patterns of the occupants can be captured. Therefore, this developed CMOS-MEMS sensor will not only be a promising flow sensing node in the HVAC system, but also potentially be used for the nonvisible and private occupant counting in buildings/rooms.

Materials Selection Approaches and Fabrication Methods in RF MEMS Switches

A state of the art review on Radio Frequency Micro-Electromechanical Systems (RF MEMS) capacitive switches is reported by considering two key aspects: (1) materials selection approaches for improving performance, and (2) fabrication methods used in capacitive MEMS switches. The beam and dielectric materials used in capacitive MEMS switches and the performance achieved through them are reviewed and reported by a rigorous literature survey. Further, materials selection approaches for the beam membrane and the dielectric layer are discussed using Ashby’s methodology, and other associated methods based on it, which uses material indices to evaluate the performance of a switch. Performance indicators for the beam materials selection are the pull-in voltage, RF loss, thermal residual stress, contact resistance, thermal conductivity, and maximum displacement, whereas the hold-down voltage, dielectric charging, leakage current, heat dissipation, capacitance ratio, and stability are performance indicators in dielectric materials selection. MEMS switch fabrication can be achieved through bulk micromachining processes and surface micromachining processes, but the surface micromachining process has been preferred over the last few decades. The fabricated MEMS switch components can be integrated using a monolithic complementary metal oxide semiconductor–micro-electromechanical systems (CMOS-MEMS) process for the realization of applications in sensors, resonators, amplifiers, phase shifters, and MEMS satellite vehicles for space applications. CMOS-MEMS monolithic fabrication is discussed further with the help of fabrication process involved and the process technology. The TSMC-CMOS 0.35 $$\upmu \hbox {m}$$ technology is one of the leading technologies in CMOS-MEMS fabrication and is mainly used.

A Robust Fully-Integrated Digital-Output Inductive CMOS-MEMS Accelerometer with Improved Inductor Quality Factor

This paper presents the design, fabrication, and characterization of an inductive complementary metal oxide semiconductor micro-electromechanical systems (CMOS-MEMS) accelerometer with on-chip digital output based on LC oscillators. While most MEMS accelerometers employ capacitive detection schemes, the proposed inductive detection scheme is less susceptible to the stress-induced structural curling and deformation that are commonly seen in CMOS-MEMS devices. Oscillator-based frequency readout does not need analog to digital conversion and thus can simplify the overall system design. In this paper, a high-Q CMOS inductor was connected in series with the low-Q MEMS sensing inductor to improve its quality factor. Measurement results showed the proposed device had an offset frequency of 85.5 MHz, sensitivity of 41.6 kHz/g, noise floor of 8.2 mg/√Hz, bias instability of 0.94 kHz (11 ppm) at an average time of 2.16 s, and nonlinearity of 1.5% full-scale.

Temperature-compensated CMOS-MEMS resonators via electrical stiffness frequency pulling

A passively temperature-compensated micromechanical resonator based on an electrical stiffness frequency pulling technique was demonstrated. In particular, a 2.92 MHz free–free beam resonator achieved by a 0.35 µm 2-poly-4-metal complementary metal-oxide semiconductor microelectromechanical systems (CMOS-MEMS) process platform yields a nearly zero first-order temperature coefficient of frequency (TCF1), from −69.78 ppm °C−1 of an uncompensated version to +0.43 ppm °C−1, and a 12× lower overall frequency drift from the uncompensated 5885 ppm to 496 ppm between 0 °C and 85 °C. The electrical stiffness compensation technique previously demonstrated on a CMOS-incompatible poly-Si surface micromachining process consumes no dc power consumption in contrast to other active methods. In this work, an improved design of the in-plane U-shaped compensating electrode allows not only the employment by a standard CMOS process but also layout-defined temperature dependency of the electrical stiffness via varying the length of the compensating electrode. A theoretical model predicts the thermally induced extension of the compensating electrode and further leads to an optimum electrode length which allows the use of only one voltage source for both compensation and polarization bias voltages. The measured results are compared with the analytical model prediction and discussion on the effects of process induced device parameter variations is presented.

A CMOS-Integrated MEMS Platform for Frequency Stable Resonators-Part I: Fabrication, Implementation, and Characterization

This paper introduces the comprehensive design concepts, procedure, and post-process flow of a robust manufacturing platform for complementary metal-oxide- semiconductor microelectromechanical systems (CMOS-MEMS) resonant transducers with enhanced frequency stability and capacitive-transduction efficiency. Thanks to a sandwich-stacking configuration of the interconnection metal line (TiN/AlCu/TiN) existing in standard CMOS technology, a deep-submicron TiN-to- TiN gap is successfully demonstrated by removing the central AlCu alloy layer through the proposed post-fabrication platform, thus realizing a novel titanium nitride composite (TiN-C) structure. Compared with the traditional release approaches utilized in the general post-CMOS fabrication, the proposed TiN composite transducer with TiN-to-TiN gap can simultaneously attain (i) a 400nm air gap for effective electrostatic transduction, (ii) adequate material selection and arrangement for near-zero frequencytemperature coefficient, and (iii) conductive electrodes to overcome frequency drift induced by dielectric charging during capacitive operation. In Part I of this study, the design guideline, layout rules, and detailed post-fabrication flow are addressed. The fabrication results of each post-process step are also exhibited. Numerical analysis, experiment results, and further discussions in terms of frequency stability for resonant transducers will be covered in Part II. [2018-0230]

Thin-Film MOSFET-Based Pressure Sensor

This paper proposes a silicon-on-insulator (SOI) complementary metal-oxide semiconductor (CMOS) micro-electromechanical system (MEMS) thin-film pressure sensor in which the sensing elements are based on stress sensitive MOSFETs, and the carrier mobility and channel resistance vary with applied pressure. Four MOSFETs are embedded within a silicon dioxide membrane to form a Wheatstone bridge. The sensors are fabricated in a commercial foundry with p-channel and n-channel designs both investigated. The fabricated pMOSFET design gave a pressure sensitivity of 5.21 mV/kPa whilst the nMOSFET gave about half the sensitivity at 2.40 mV/kPa. This was coupled with maximum power consumption of 0.19 mW and 0.39 mW for the pMOSFET and nMOSFET respectively. This shows a highly sensitive pressure sensor, with improved sensitivity on traditional piezoresistors as well as significantly higher sensitivity than current MOSFET based pressure sensors. Moreover, the maximum DC power consumption was only 190 µW and 390 µW for the pMOSFET and nMOSFET, respectively. This novel low-cost, low-power, high-sensitivity CMOS MEMS technology with on-chip electronics could be used towards the implementation of MOSFET based pressure transduction in a multitude of industrial and other applications.

Application of Taguchi Signal to Noise Ratio Design Method to ZnO Thin Film CMOS SAW Resonators

A systematic approach using Taguchi method is proposed for optimization of complementary metal oxide semiconductor microelectromechanical system surface acoustic wave (SAW) resonators. The aim of the present method is to enhance the performance of SAW devices in terms of electromechanical coupling coefficient while reducing the design and development cost. Controllable factors such as a number of transducers, N t , the distance between input and output transducers, L c , and the thickness of the piezoelectric materials, T c have been optimized. L 27 (3 13 ) orthogonal array was chosen to conduct 27 simulations with three level parameters. Time and cost efficient 2D finite element simulations were done using COMSOL Multiphysics™ for two-step analysis Eigen frequency and frequency domain analysis. The orthogonal array, signal to noise ratio, and analysis of variance (ANOVA) were calculated to determine the best settings of the design parameters. The maximum electromechanical coupling coefficient is achieved at the optimal condition of N = 6; L c = 1.6 μm; T c = 2.5 μm with increased performance by 4.68% for κ 2 and 9.62% for G 12 (f ) compared to the initial conditions. The interaction between pairs of factors has also been investigated. The Taguchi method reveals that both N t and L c , and the interaction of N t × L c plays crucial roles in optimizing the electroacoustic conversion of the SAW devices. Hence, the experiment shows that the performance of the SAW device has been successfully optimized.

Design of a CMOS MEMS Accelerometer Used in IoT Devices for Seismic Detection

This paper reports a design for a complementary metal oxide semiconductor (CMOS) microelectromechanical system accelerometer used in Internet of Things (IoT) devices for seismic detection. The proposed device performs the main functions of accelerometers, and has the advantage of automatically selecting the electrostatic force of feedback to null the position of the sensor. This paper applied $0.35~\mu \text{m}$ 2P4M CMOS technology with a 3-V power supply. The sensitivity of the continuous time voltage analog sensing circuits was 131.99 mV/g and the maximal nonlinearity was 1.21% over the excitation of 0.25 to 6.75 g (1 g = 9.8 m/s2) intensity. The noise floor was 0.579 mg/Hz1/2. The cross-axis Y and cross-axis Z nonlinearity were less than 0.05% and 1.38%, respectively. Under an excitation of 2.75 g intensity, the peak signal-to-noise-plus-distortion ratio (SNDR) of the proposed accelerometer was 72 dB, and decreased to 49.1 dB after 3 weeks of continuous shaking. After enabling automatically nulling of the sensor for 0.5 s period of time, the peak SNDR was 75.2 dB. Based on this operational mode, the nulling accelerometer could be applied for usage in IoT devices for seismic detection. The measurement results verify the functions and performance of the proposed accelerometer. Experimental monitoring of river bridge vibration was also successfully conducted.

CMOS MEMS Hot-Film Thermoelectronic Flow Sensor

In this article, we present a complementary metal-oxide semiconductor microelectromechanical system (CMOS MEMS) thermoelectronic flow sensor and discuss the advantages of employing anemometric and calorimetric transduction principles simultaneously. This readout concept exploits the fact that anemometric flow sensors take advantage of the maximum temperature generated within the device and, thus, are provided with the maximum flow sensitivity, while calorimetric flow sensors have the temperature sensing elements placed away from this maximum temperature region and, thus, are intrinsically less sensitive. At the same time, fluid flow direction discrimination in bidirectional flow sensors can be achieved by simply looking at the polarity of the differential signal coming from the temperature sensors placed aside the heating element. We also show that thermoelectronic flow sensors can benefit by having temperature sensors formed by an array of diodes to further enhance the device sensitivity. Although we apply these concepts to a sensor with a nonoptimum design and lacking any support electronics (e.g., filters, amplifiers, constant temperature driving circuitry, etc.), results are among the best ever reported in literature (including non-CMOS technologies), thus showing the high potential of our technology.

Curvature of BEOL Cantilevers in CMOS-MEMS Processes

This paper presents the curvature characterization results of released back-end-of-line $5~\mu \text{m}$ -wide cantilevers for two different 0.18- $\mu \text{m}$ 1P6M complementary metal–oxide semiconductor microelectromechanical systems processes. Results from different runs and lots from each foundry are presented. The methodology and accuracy of the characterization approach, based on optical measurements of test cantilever curvature, are also discussed. Special emphasis is given to the curvature average and variability as a function of the number of stacked layers. Analythical equations for modeling the bending behavior of stacked cantilevers as a function of the tungsten (W) vias that join the metal layers are presented. In addition, the effect of various post-processing conditions and design techniques on the curvature of both single and stacked cantilevers is analyzed. In particular, surpassing certain time-dependent temperature stress conditions after release lead to curvature shifts larger than one order of magnitude. Also, the W via design was found to strongly affect the curvature of the test cantilevers. [2016-0293]

Enhanced piezoelectric properties of aluminium doped zinc oxide thin film for surface acoustic wave resonators on a CMOS platform

The increase in frequency spectrum for wireless communication system has led to the growing interest in thin film electroacoustic technology that scales favorably upon miniaturization. Non-ferroelectric piezoelectric thin films such as Zinc Oxide is one of the most promising material for Complementary Metal Oxide Semiconductor-Microelectromechanical system (CMOS-MEMS) integration due to its silicon compatibility and good piezoelectric properties. This paper compares ZnO and Al doped ZnO (AZO) thin films performance characteristics when applied as CMOS-based surface acoustic wave (SAW) resonators. The interdigitated electrodes were fabricated using 0.35 μm CMOS technology followed by piezoelectric thin film deposition and probe pad patterning. Pure ZnO and AZO with 2 wt% Al2O3 have been prepared by pulse laser deposition and RF magnetron sputtering respectively. Both deposited ZnO and AZO thin films exhibited preferential crystalline growth in 002 direction. EDS analysis confirmed the incorporation of aluminium in zinc oxide thin films. High frequency electrical measurement results revealed that the devices with AZO thin film have enhanced performances as compared to devices based on ZnO thin film. It is shown that the insertion loss for AZO thin film was reduced from −65.1 to −53.5 dB and the quality factor was enhanced from 11.33 to 25.81. More significantly, the electromechanical coupling coefficient and piezoelectric coefficient were enhanced from κ = 0.044–0.069% and d31 = 5.00 to 5.41 pm/V for AZO devices compared to those based on ZnO devices, respectively. One possible explanation of these enhanced piezoelectric properties comes from the almost ideal c-axis orientation of AZO thin film as compared to pure ZnO thin films. Our results suggest that the AZO thin film can be a better candidate for surface acoustic wave resonator using the CMOS-MEMS platform.

A CMOS Compatible MEMS Pirani Vacuum Gauge with Monocrystal Silicon Heaters and Heat Sinks**Supported by the National High Technology Research and Development Program of China under Grant No 2015AA042602.

We present a micro-Pirani vacuum gauge using the low-resistivity monocrystal silicon as the heaters and heat sinks fabricated by the post complementary metal oxide semiconductor (CMOS) microelectromechanical system (MEMS) process. The metal interconnection of the device is fabricated by a 0.5 μm standard CMOS process on 8-inch silicon wafer. Then, a –Si low-temperature fusion bonding is developed to bond the CMOS wafer and the MEMS wafer, with the electrical connection realized by the tungsten through silicon via process. Wafer-level AlGe eutectic bonding is adopted to package the Pirani gauge in a non-hermetic cavity to protect the gauge from being damaged or contaminated in the dicing and assembling process, and to make it suitable for actual applications. To increase the accuracy of the test and restrain negative influence of temperature drift, the Wheatstone bridge structure is introduced. The test results show that before capping, the gauge has an average sensitivity of 1.04 × K· in dynamic range of 0.01–20 Torr. After capping, the sensitivity of the gauge does not decrease but increases to 1.12 × K· .

Design of CMOS‐MEMS broadband infrared emitter arrays integrated with metamaterial absorbers based on CMOS back‐end‐of‐line

A new design of complementary metal–oxide–semiconductor microelectromechanical systems (CMOS-MEMS) broadband infrared (IR) emitter arrays with integrated metamaterial absorbers (MAs) developed by the CMOS back-end-of-line is presented. The IR emitter array is a promising broadband thermal radiation source for integrated gas sensors. Novel IR emitter arrays are designed using the Central Semiconductor Manufacturing Corporation 0.5 μm 2-poly-3-metal CMOS process. To improve the low emissivity that is commonly seen in CMOS-MEMS type IR emitters due to the inherited low emissivity of SiO2 and SiN in CMOS process, we newly adopted tri-layer metal–insulator–metal (MIM) and four-layer insulator–MIM (IMIM) MA by using the CMOS back-end metal layers and inter-layer dielectrics, thereby to excite multi-mode surface plasmon polariton resonances. The emitter integrated with IMIM MA can be electrically modulated up to 344 Hz, as theoretically predicated from thermal properties of the emitters and the radiation properties calculated based on Planck's radiation law. Simulated emissivity spectra through FEM show that the multi-mode resonances in CMOS MIM and IMIM MAs enhance emissivity and broaden the waveband effectively.

A CMOS MEMS Humidity Sensor Enhanced by a Capacitive Coupling Structure.

A capacitive coupling structure is developed to improve the performances of a capacitive complementary metal oxide semiconductor (CMOS) microelectromechanical system (MEMS) humidity sensor. The humidity sensor was fabricated by a post-CMOS process. Silver nanowires were dispersed onto the top of a conventional interdigitated capacitive structure to form a coupling electrode. Unlike a conventional structure, a thinner sensitive layer was employed to increase the coupling capacitance which dominated the sensitive capacitance of the humidity sensor. Not only static properties but also dynamic properties were found to be better with the aid of coupling capacitance. At 25 °C, the sensitive capacitance was 11.3 pF, the sensitivity of the sensor was measured to be 32.8 fF/%RH and the hysteresis was measured to be 1.0 %RH. Both a low temperature coefficient and a fast response (10 s)/recovery time (17 s) were obtained.

Experimental Analysis of Vapor HF Etch Rate and Its Wafer Level Uniformity on a CMOS-MEMS Process

This paper presents the characterization results of the release step with vapor hydrofluoric acid on a Complementary Metal Oxide Semiconductor-Microelectromechanical Systems (CMOS-MEMS) process obtained with a new methodology for controlling the release etch process of CMOS-MEMS devices. The effect of release hole size on etch rate and uniformity was investigated. No appreciable effects were observed for release hole sizes between 0.48 and 1 $\mu \text{m}^{2}$ . With-in-wafer uniformity better than 3% and wafer-to-wafer variability better than 2.5% were found, while achieving constant etch rates of $\sim 0.25~\mu $ mmin $^{-1}$ and maintaining the required selectivity. The new characterization methodology is based on monitoring capacitance values of a set of test structures distributed across the analyzed wafers rather than monitoring oxide undercuts. A new parameter defined as etch ratio greatly improved the accuracy of this methodology by removing undesirable contributions to the capacitance coming from sources not related to the release process itself. Results showed that this methodology provides a characterization accuracy one order of magnitude better than what was achieved with a method based on optical measurements of oxide lateral undercuts. [2015-0290]

Fabrication of a Micromachined Capacitive Switch Using the CMOS-MEMS Technology

The study investigates the design and fabrication of a micromachined radio frequency (RF) capacitive switch using the complementary metal oxide semiconductor-microelectromechanical system (CMOS-MEMS) technology. The structure of the micromachined switch is composed of a membrane, eight springs, four inductors, and coplanar waveguide (CPW) lines. In order to reduce the actuation voltage of the switch, the springs are designed as low stiffness. The finite element method (FEM) software CoventorWare is used to simulate the actuation voltage and displacement of the switch. The micromachined switch needs a post-CMOS process to release the springs and membrane. A wet etching is employed to etch the sacrificial silicon dioxide layer, and to release the membrane and springs of the switch. Experiments show that the pull-in voltage of the switch is 12 V. The switch has an insertion loss of 0.8 dB at 36 GHz and an isolation of 19 dB at 36 GHz.

Fabrication and Characterization of a CMOS-MEMS Humidity Sensor.

This paper reports on the fabrication and characterization of a Complementary Metal Oxide Semiconductor-Microelectromechanical System (CMOS-MEMS) device with embedded microheater operated at relatively elevated temperatures (40 °C to 80 °C) for the purpose of relative humidity measurement. The sensing principle is based on the change in amplitude of the device due to adsorption or desorption of humidity on the active material layer of titanium dioxide (TiO2) nanoparticles deposited on the moving plate, which results in changes in the mass of the device. The sensor has been designed and fabricated through a standard 0.35 µm CMOS process technology and post-CMOS micromachining technique has been successfully implemented to release the MEMS structures. The sensor is operated in the dynamic mode using electrothermal actuation and the output signal measured using a piezoresistive (PZR) sensor connected in a Wheatstone bridge circuit. The output voltage of the humidity sensor increases from 0.585 mV to 30.580 mV as the humidity increases from 35% RH to 95% RH. The output voltage is found to be linear from 0.585 mV to 3.250 mV as the humidity increased from 35% RH to 60% RH, with sensitivity of 0.107 mV/% RH; and again linear from 3.250 mV to 30.580 mV as the humidity level increases from 60% RH to 95% RH, with higher sensitivity of 0.781 mV/% RH. On the other hand, the sensitivity of the humidity sensor increases linearly from 0.102 mV/% RH to 0.501 mV/% RH with increase in the temperature from 40 °C to 80 °C and a maximum hysteresis of 0.87% RH is found at a relative humidity of 80%. The sensitivity is also frequency dependent, increasing from 0.500 mV/% RH at 2 Hz to reach a maximum value of 1.634 mV/% RH at a frequency of 12 Hz, then decreasing to 1.110 mV/% RH at a frequency of 20 Hz. Finally, the CMOS-MEMS humidity sensor showed comparable response, recovery, and repeatability of measurements in three cycles as compared to a standard sensor that directly measures humidity in % RH.

Multi-frequency CMOS oscillator based on CMOS MEMS SAW resonator

This paper presents the design and simulation results for a multi-frequency oscillator based on complementary metal oxide semiconductor (CMOS) microelectromechanical systems (MEMS) surface acoustic wave (SAW) resonator. Multi-frequency oscillator is simulated using 0.35 µm CMOS technology. The oscillator operated at 600 and 1.76 GHz. The multi-frequency oscillator shows phase noise performance of ?67.35 and ?92.83 dBc/Hz at 100 kHz offset frequency for 600 MHz and 1.76 GHz, respectively, during simulation. The pierce circuit topology was used to sustain the oscillation from CMOS SAW resonator. The sustaining circuit was design and fabricated in 0.35 µm CMOS technology process with 3.3 V supply. The measured S21 of sustaining circuit topology are 6 and 2 dB at 1.76 GHz and 600 MHz, respectively. The phase responses for 1.76 GHz and 600 MHz are ?50° and ---200° correspondingly.